docs: def call_proxy_api(self, event):
          """Make a request against the API defined by this app.
  
          Return any result from the API call as a dict that is expected by the
          AWS_PROXY type integration in API Gateway.
  
          :param dict event:
              Dictionary containing the entire request payload passed to the
              Lambda function handler.
          :returns:
              Dictionary containing the response data from the API endpoint.
          :raises:
              :class:`fleece.httperror.HTTPError` on 4xx or 5xx responses from
              the API endpoint handler, or a 500 response on an unexpected
              failure (due to a bug in handler code, for example).
          """
          try:
              environ = build_wsgi_environ_from_event(event)
              response = werkzeug.wrappers.Response.from_app(self, environ)
              return {
                  'statusCode': response.status_code,
                  'headers': {
                      header: value for header, value in response.headers.items()
                  },
                  'body': response.get_data(as_text=True),
              }
          except Exception:
              # We should actually never get here, because exceptions raised
              # within the application are handled by the error handlers, and the
              # default one will return a clean 500 error during the happy path
              # above.
              self.logger.exception('Unhandled exception')
              return {
                  'statusCode': 500,
                  'headers': {},
                  'body': json.dumps({
                      'error': {
                          'message': 'Internal server error.',
                      },
                  }),
              }